16.18.2. Activate the filter

You can find this filter in the image window menu under
Filters → Alpha to Logo → Particle Trace….

16.18.3. Options

Figure 17.416. “Particle Trace” options

Border size (pixels)

Actually this option is the text layer's border of the
“Particle Trace” Script-Fu Logo (hence the misleading
name). Here it determines the width of the white shadow's
feathering.

Hit rate

This option sets the amount of light points produced by the
Noise filter and thus the
amount of points converted to
sparkles. The value ranges
from from 0.0 to 1.0, but some values may be not useful:

Figure 17.417. “Hit rate” examples

Hit rate 0.10

Hit rate 0.25

Hit rate 0.40

Edge width

Along the edge of the alpha, a new area will be created with
radius “Edge width” (compare
Section 4.13, “Border”). This area will also be
filled with the “Base color”, but will be a bit
darker.

Edge only

If checked, the filter effect will be applied to the edge of the
alpha channel only and the area of the alpha channel will be
cleared.

“Edge only” activated

Base color

This color is used to fill the area defined by the active layer's
alpha channel. It defaults to a very dark green. As usual,
clicking on the color swatch button opens a color selector where
you can choose any other color.

Background color

This color is used to fill a new background layer. Note that above
the background layer there is a white shadow layer which has
opacity set to 90%, so you will see the background color only
partially. If the “Edge only” option is enabled, the
area of the alpha channel will be cleared and you will see the
background color. Again, when you click on the color swatch
button, a color selector pops up where you can select any color.

The active layer (top) and the filter layers below

16.18.4. Filter details

The filter adds noise to the
alpha and then turns the spots into
sparkles. Then it adds a
feathered white shadow.